Centrifugal impeller



RRHurrso CENTRIFUGAL IMPELLER July 1, 1941.

Filed Aug. 13, 1940 Inventor. \QObeTt. F2. Hu'ltson, b 6.2

tor'hey- Patented July I, 1941 CENTRIFUGAL IMPELLER Robert R. Huitson,Rugby, England, assignor to General Electric Company, a corporation ofNew Yo k Application August 13, 1940, Serial No. 352,428 In GreatBritain August 11, 1939 2 Claims.

The present invention relates to centrifugal impellers for compressors,blowers, pumps and the like. More specifically the invention relates tothe type of impellers which include an impeller disk and a plurality ofcircumferentially spaced, substantially radially directed blades orvanes secured to or integrally formed with the disk and a shroud band orring attached to the blades opposite the disk. The shroud band or rimduring operation is subject to considerable centrifugal forces. Thisrequires a firm connection between the shroud band and the impellerblades.

One object of my invention is to provide an improved construction andarrangement of centrifugal impellers whereby the impeller shroud band isfirmly attached to the impeller blades.

For a consideration of what I believe to be novel and my invention,attention is directed to the following description and the claimsappended thereto in connection with the accompanying drawing.

In the drawing Fig. 1 illustrates a top view of an impeller embodying myinvention; Fig. 2 is a front view partly in section taken along lines2-2 of Fig. 1; Figs. 3 and 4 are perspective views showing a shroud bandin two successive stages of manufacture; and Figs. 5 and 6 are exploded,perspective Views of the impeller.

An impeller according to my invention, as shown in Figs. 1 and 2,comprises a disk Ill having a central portion with a bore forming a hubI II for attachment to an impeller shaft, not shown. A plurality ofcircumferentially, uniformly spaced blades I2 are secured, in thepresent instance integrally formed with the disk III. A shroud band I3is attached to the edges of the blades opposite the disk ID. The band I3has an inner cylindrical portion I4 and an outer substantiallycomically-shaped portion I5 the thickness of which decreases radially inoutward direction. The connection between the band I3 and the edges ofthe blades I2 is accomplished by two rows of dovetailed projections I 6and Il integrally formed on the shroud band I3 and located incorresponding dovetailed recesses I8 and I9 respectively of the bladesI2. Each blade has an outer edge 20 forming two radially spaceddovetailed recesses I8, I9 for receiving two dovetailed projections I6,ll of the shroud band I3. In order to retain the dovetailed projectionswithin the recesses, that is, to prevent relative circumferentialmovement between the blades and the shroud band, means ar provided topreclude relative rotational movement between the shroud band and theimpeller blades. These means in the present instance are in the form oftwo locking members or plates 2| and 22 arranged on diametricallyopposite sides of the shroud band and fastened thereto by means ofrivets 23. The plates 2|, 22 have end faces 24 engaging ad acent facesof a pair of impeller blades I2, thereby preventing circumferentialrelative movement between the blades and the shroud band.

During the manufacturing process two radially spaced rows of dovetailedrecesses are machined into the edges 20 of the blades after the latterhave been secured to or integrally formed on the disk Ill. Thedovetailed projections I6, I! in the shroud band are formed by producinga shroud band'and machined thereon two annular undercut projections 25and 26, as shown in Fig. 3. Intermediate portions of the annularprojections 25, 26 are then removed or cut away, thus leaving two rowsof dovetailed projections I6, II, as shown in Fig. 4. After completionof the blades and the shroud band the latter is assembled with theblades by rotating it so that the projections I6, Il enter and fill therecesses I8, l9 respectively. Finally, the locking plates 22 areattached to the shroud band securely to lock the latter to the bladesand to prevent relative movement between them.

Having described the method of operation of my invention, together withthe apparatus which I now consider to represent the best embodimentthereof, I desire to have it understood that the apparatus shown is onlyillustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent in the UnitedStates is:

1. Centrifugal impeller comprising a disk with a plurality ofcircumferentially spaced substantially radially directed blades eachhaving an edge engaging the disk, a shroud band engaging the other edgesof the blades, dovetailed connecting means formed on the other edges ofthe blades and the shroud band rigidly to secure the band to the blades,and locking plate means fastened to the shroud band and engagingadjacent faces of a pair of blades to prevent relative circumferentialmovement between the blades and the band.

2. Centrifugal impeller comprising a disk with a plurality ofcircumferentially spaced blades each having an edge secured to the disk,a shroud band engaging the other edges of the blades, dovetailedconnecting means formed on the other edges of the blades and the shroudband rigidly to secure the band to the blades, and locking meansfastened to the shroud band and engaging adjacent faces of a pair ofblades to prevent relative circumferential movement between the bladesand the band.

ROBERT R. HUITSON.

